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The dilemma of using a shoulder belt force limiter with a 3-point belt system is selecting a limit load that will balance the reduced risk of significant thoracic injury due to the shoulder belt loading of the chest against the increased risk of significant head injury due to the greater upper torso motion allowed by the shoulder belt load limiter. However, with the use of air bags, this dilemma is more manageable since it only occurs for non-deploy accidents where the risk of significant head injury is low even for the unbelted occupant. A study was done using a validated occupant dynamics model of the Hybrid III dummy to investigate the effects that a prescribed set of shoulder belt force limits had on head and thoracic responses for 48 and 56 km/h barrier simulations with driver air bag deployment and for threshold crash severity simulations with no air bag deployment.

This paper describes an analytical method to predict the sensor closure time for an airbag (Supplemental Inflatable Restraint - SIR) system in frontal impacts. The analytical tools used are the explicit finite element code, an in-house sensor closure time prediction program, and a full vehicle finite element model. Nodal point information obtained from the full vehicle finite element simulation is used to predict the sensor closure time of the airbag system. This analytical method can provide the important crash signature information for a SIR system development of a new vehicle program. In this paper, 0-degree frontal impacts at four different impact speeds with two different bumper energy absorption systems are studied using the non-linear finite element computer program DYNA3D. It is concluded that this analytical method is very useful to predict the SIR sensor closure time.

Although rollover crashes represent a small fraction (approximately 3%) of all motor vehicle crashes, they account for roughly one quarter of crash fatalities to occupants of cars, light trucks, and vans (NHTSA Traffic Safety Facts, 2004). Therefore, the National Highway Traffic Safety Administration (NHTSA) has identified rollover injuries as one of its safety priorities. Motor vehicle manufacturers are developing technologies to reduce the risk of injury associated with rollover collisions. This paper describes the development by General Motors Corporation (GM) of a suite of laboratory tests that can be used to develop sensors that can deploy occupant protection devices like roof rail side air bags and pretensioners in a rollover as well as a discussion of the challenges of conducting this suite of tests.

Static deployments of driver-side airbags into the legs of human subjects were used to investigate the effects of inflator capacity, internal airbag tethering, airbag fabric, and the distance from the module on airbag-induced skin abrasion. Abrasion mechanisms were described by measurements of airbag fabric velocity and target surface pressure. Airbag fabric kinematics resulting in three distinct abrasion patterns were identified. For all cases, abrasions were found to be caused primarily by high-velocity fabric impactrather than scraping associated with lateral fabric motion. Use of higher-capacity inflators increased abrasion severity, and untethered airbags produced more severe abrasions than tethered airbags at distances greater than the length of the tether. Abrasion severity decreased as the distance increased from 225 to 450 mm. Use of a finer-weave airbag fabric in place of a coarser-weave fabric did not decrease the severity of abrasion.

Aspirating airbag modules are unique from other designs in that the gas entering the airbag is a mixture of inflator-delivered gas and ambient-temperature air entrained from the atmosphere surrounding the module. Today's sophisticated computer simulations of an airbag deployment typically require as input the mass-flow rate, chemical composition and thermal history of the gas exiting the canister and entering the airbag. While the mass-flow rate and temperature of the inflator-delivered gas can be obtained from a standard tank test, information on air entrainment into an aspirated canister is limited. The purpose of this study is to provide quantitative information about the aspirated mass-flow rate during airbag deployment. Pressure and velocity measurements are combined with high-speed photography in order to gain further insight into the relationship between the canister pressure, the rate of cabin-air entrainment and the airbag deployment.

A deformable finite element dummy model was used to simulate air bag interaction with in-position passenger side occupants in frontal vehicle crash. This dummy model closely simulates the Hybrid III hardware with respect to geometry, mass, and material properties. Test data was used to evaluate the validity of the model. The calculated femur loads, chest acceleration and head acceleration were in good agreement with the test data. A semi-rigid dummy model (with rigid chest) was derived from the deformable dummy to improve turnaround time. Simulation results using the semi-rigid dummy model were also in reasonable agreement with the test data. For comparison purpose, simulations were also performed using PAMCVS, a hybrid code which couples the finite element code PAMCRASH with the rigid body occupant code. The deformable dummy model predicted better chest acceleration than the other two models.

The nature of the potentially hazardous interaction between a passenger-side airbag and a rear-facing child restraint is described, as well as the expectations regarding airbag interaction with other types of child restraint systems. Progress made in developing tools to study the problem and test criteria to evaluate possible solutions are summarized, efforts to inform the public are noted, and promising directions for dealing with the problem are addressed. Primary emphasis is placed on the work of the Society of Automotive Engineers (SAE) Child Restraint and Airbag Interaction (CRABI) Task Force and that of its members.

The air bag safety issues became evident in 1995 and other factors have conjoined to change the climate regarding motor vehicle safety. Traditionally, motor vehicle safety issues have been evaluated based upon the effects upon average adult males. The new climate requires consideration of the effects on persons of differing size and gender. By including consideration of children and women, rulemaking and the applied technologies are able to better optimize safety than is the case when rules are focused only on the average adult male. Automotive electronics serves a key role in the migration from a one-size-fits- all protection to a more customized protection for a variety of occupants. The enhancements have been the most prominent in the area of sensing, be it the sensing and characterization of the crash itself, or the sensing and characterization of occupants in the vehicle.

An objective, biomechanically based assessment is made of the risks of life-threatening brain injury of frontal crash test results. Published 15 ms HIC values for driver and right front passenger dummies of frontal barrier crash tests conducted by Transport Canada and NHTSA are analyzed using the brain injury risk curve of Prasad and Mertz. Ninety-four percent of the occupants involved in the 30 mph, frontal barrier compliance tests had risks of life-threatening brain injury less than 5 percent. Only 3 percent had risks greater than 16 percent which corresponds to 15 ms HIC > 1000. For belt restrained occupants without head contact with the interior, the risks of life-threatening brain injury were less than 2 percent. In contrast, for the more severe NCAP test condition, 27 percent of the drivers and 21 percent of the passengers had life-threatening brain injury risks greater than 16 percent.

Aircraft used for business (executive corporate transportation or personal business) and utility purposes now represent about one-third of the total United States aircraft inventory. Data from accident investigation of business aircraft involved in survivable accidents indicate serious injuries and fatality to the occupants occur most frequently as a result of the unprotected head and neck or chest flailing in contact with aircraft controls, instrument panel, or structure. Improvement of current aircraft to provide increased occupant safety and survival during crash impacts is both necessary and feasible. Design considerations include folding seat back locks to prevent collapse, increased seat tie-down to structure, instrument panels and glare shields designed to absorb energy through structural design and padding, stronger seat structure, lateral protection, design and packaging of knobs and projections to minimize injury in contact, and installation of upper torso restraint.

This study is an extension of previous work on driver air bag deployment loads which used the mid-size male Hybrid Ill dummy. Both small female and mid-size male Hybrid Ill dummies were tested with a range of near-positions relative to the air bag module. These alignments ranged from the head centered on the module to the chest centered on the module and with various separations and lateral shifts from the module. For both sized dummies the severity of the loading from the air bag depended on alignment and separation of the dummy with respect to the air bag module. No single alignment provided high responses for all body regions, indicating that one test at a typical alignment cannot simultaneously determine the potential for injury risk for the head, neck, and torso. Based on comparisons with their respective injury assessment reference values, the risk of chest injury appeared similar for both sized dummies.

The greatest demand facing the automotive industry has been to provide safer vehicles with high fuel efficiency at minimum cost. Current automotive vehicle structures have one fundamental handicap: a short crumple zone for crash energy absorption. This leaves limited room for further safety improvement, especially for high-speed crashes. Breakthrough technologies are needed. One potential breakthrough is to use active devices instead of conventional passive devices. An innovative inflatable bumper concept [1], called the “I-bumper,” is being developed by the authors for crashworthiness and safety of military and commercial vehicles. The proposed I-bumper has several active structural components, including a morphing mechanism, a movable bumper, two explosive airbags, and a morphing lattice structure with a locking mechanism that provides desired rigidity and energy absorption capability during a vehicular crash.

In the I-bumper (inflatable bumper) concept [1], two explosive airbags are released just before the main body-to-body crash in order to absorb the kinetic energy of colliding vehicles. The release also actuates other components in the I-bumper, including a movable bumper and an energy absorption morphing lattice structure. A small explosive charge will be used to deploy the airbag. A conventional airbag model will be used to reduce the crash energy in a controlled manner and reduce the peak impact force. An analytic model of the explosive airbag is developed in this paper for the I-bumper system and for its optimal design, while the complete system design (I-bumper) will be discussed in a separate paper. Analytical formulations for an explosive airbag will be developed and major design variables will be identified. These are used to determine the required amount of explosive and predict airbag behavior, as well to predict their impact on the I-bumper system.

Using a combination of engineering test experience, explicit finite-element analysis, and advanced materials characterization, a predictive engineering method has been developed that can assist in the development of active top pads. An active top pad is the component of the instrument panel that covers the passenger airbag module and articulates during a crash event, allowing the airbag to deploy. This paper highlights the predictive analysis method, analytical results interpretation, and suggestions for future development.

Airbag systems have been part of passenger car and truck programs since the mid-1980's. However, systems designed for medium and heavy duty truck applications are relatively new. The release of airbag systems for medium duty truck has provided some unique challenges, especially for the airbag sensing systems. Because of the many commercial applications within the medium duty market, the diversity of the sensing environments must be considered when designing and calibrating the airbag sensing system. The 2003 Chevrolet Kodiak and GMC TopKick airbag sensing development included significant work, not only on the development of airbag deployment events but also non-deployment events – events which do not require the airbag to deploy. This paper describes the process used to develop the airbag sensing system deployment events and non-deployment event used in the airbag sensing system calibration.